In-depth Energy Efficiency Reviews are undertaken of countries that volunteer to host such an exercise. They are based on a peer review by representatives of 3-4 other countries and the Secretariat. The in-depth Energy Efficiency Reviews analyse the broad economic and energy context of the country, patterns of energy use, energy efficiency policies and institutional frameworks. They include specific recommendations to national governments concerning possible improvements to their national energy efficiency policies and programmes. These recommendations are discussed and endorsed by the Working Group on Energy Efficiency and Related Environmental Aspects and by the Energy Charter Conference (the organisation's governing body). After 2 to 3 years, countries report back to the Working Group on the implementation of the recommendations.

Regular reviews assist with the monitoring the implementation of the Energy Charter Treaty and PEEREA and with additional cross-country analysis. They are based on a review format agreed by the Working Group and divided into two parts: Part I focuses on energy efficiency legislation, policies and programmes; Part II covers quantitative data on energy and energy efficiency.